I. Field of the Invention
This invention relates generally to septic tank cover systems, and more particularly to septic tank cover systems which are designed to provide access to septic tanks, seal septic tanks from water, and prevent tank leakage.
II. Discussion of the Prior Art
It is well known that access to septic tanks buried underground is periodically needed so that material can be pumped from the tank and maintenance performed. It is important for structures which provide access to the tanks to maintain a water tight environment leading to the buried septic system. The seals for these structures are greatly susceptible to leaks due to their exposure to an outdoor conditions. Frost heaving, forces related to vertical ground movement, and rotational forces due to lateral ground movement can each have a potentially detrimental impact on the integrity of septic tank access structures.
To improve the longevity and durability of access points to septic tanks, it is desirable, as much as possible, to protect the structure from potentially damaging types of ground forces. Various aspects of these problems have been addressed in some previous disclosures although a design specifically suited to properly address these concerns has never been as fully and effectively designed before. For example, in the Meyers. U.S. patent application Pub. No. 2003/0145527, a riser component for an on-site waste system is described which incorporates a riser pan, a cover, and various interconnecting riser elements. The Airhart U.S. Patent Application Pub. No. 2004/0040221 is directed at a molded manhole unit. This application shows a unit with a manifold riser having a beveled riser edge, a riser extension which mates with the manifold riser, a sealing ring, and a riser cap.
The present invention offers important advantages over the prior art due to new concepts included in its design. Specifically, the arrangement of the riser base of the present invention offers several superior features not found in the prior art. These features relate to the ledge and depressions below the ledge that allow secure anchoring of the device into a concrete casting. These advantages also include the uninterrupted surface upon which the pipe member can rest. This surface provides an effective mechanism for sealing the junction between the base and the pipe. The use of corrugated pipe also provides certain advantages in terms of cost, strength, and the ability for one to cut the pipe to length rather than having to buy a specific piece of a specific height. The invention overcomes the problems associated with using such a pipe by providing a novel sealing surface between the pipe and the top cover, a novel sealing arrangement between the riser base and the pipe, and also by providing a sleeve that covers the corrugations in the pipe to prevent the pipe from coming loose from the base due to ground forces. Finally, the manner in which the top cover of the present invention engages the pipe to provide an effective seal that is much more refined and simple than what is shown in the prior art.